With the highly developed semiconductor technology, the currently available integrated circuits (ICs) have a largely reduced volume than before. To enable the ICs to process more data, the number of elements and components included in the current ICs is often several times of that in the conventional ICs having the same volume. However, heat produced by the ICs during operation thereof increases with the growing number of electronic elements and components in the ICS. For example, the heat produced by a common central processing unit (CPU) at full working load is high enough for burning out the whole CPU. Therefore, it is important to develop effective heat radiating means for the ICs.
Generally, a heat sink is made of a metal material with high heat conductivity. In addition to the mounting of a cooling fan to carry away the heat produced by heat-producing elements, the heat sink in the form of a radiating fin assembly is frequently used to obtain an enhanced heat radiating effect. In some other cases, heat pipes are further provided on the heat sink to more quickly transfer and dissipate heat, so that products with ICs are protected against burning out.
FIG. 1 is a perspective view showing a conventional rectangular heat sink 1. Multiple radiation fins 11 are arranged in parallel to two longer sides of the heat sink 1 and equally spaced from one another. The heat sink 1 has a base 12 for directly contacting with a heat source 1A to conduct heat produced by the heat source to a main body of the heat sink 1, so that the heat is radiated from the radiation fins 11. The conventional heat sink 1 has a plurality of radiation fins 11. When the heat produced by the heat source is conducted from the heat source to the radiation fins 11 of the heat sink 1, the heat is outward diffused via gaps 111 between the radiation fins 11 and dissipates. The radiation fins 11 themselves have insufficient heat-radiating areas. Moreover, the gaps 111 between the radiation fins 11 are quite narrow and extended straightly toward two opposite sides of the heat sink 1. Under these circumstances, the conventional heat sink 1 only provides narrow spaces for dissipating heat in only two opposite horizontal directions. As a result, the conventional heat sink 1 has low ventilating efficiency which directly leads to poor heat-dissipating efficiency. Therefore, the heat produced by the heat source can be hardly effectively dissipated, and tends to stagnate around the heat sink 1. In a worse condition, the heat source 1A will become damaged due to overheating. In brief, the conventional heat sink 1 has the following disadvantages:    1. The conventional heat sink has only very small heat-radiating areas.    2. The conventional heat sink has only two opposite air outlets which are insufficient for dissipating the heat. Therefore, the heat is likely to stagnate around the heat sink or the heat source without being easily and efficiently dissipated.    3. The conventional heat sink has poor heat-dissipating efficiency.
It is therefore tried by the inventor to develop an improved heat radiating unit to solve the above problems with the conventional heat sink.